The fibre orientation distribution in a material sample extracted from an injection moulded plate, displaying the commonly encountered layered shell–core–shell structure, was analyzed. Starting from a micro-tomography reconstruction of the sample, instead of trying to isolate each single fibre and measuring its geometrical properties, we derived the components of a fabric tensor from the evaluation of a global anisotropy parameter, the mean intercept length MIL. This parameter, commonly employed for the analysis of biological and geological structures, proved to be an efficient tool for the analysis of the structure of short fibre reinforced composites. The local variations of the degree of anisotropy (ratio of the maximum and minimum eigenvalues of the fabric tensor) from the shell to the core layers of the injection moulded plate could be captured and information about the local average fibre orientation angle was also obtained
The combined effect of notches and fibre orientation on static and fatigue strength of short glass fibre reinforced polyamide 6 was studied using notched specimens that, by proper design of the mould, could be injection moulded through gates of two different sizes and locations. The results showed that the values of the tensile and fatigue notch factors for a particular geometry were strongly influenced by varying the way specimens were injected. A new experimental method was applied to investigate whether the observed differences in mechanical behaviour of specimens having the same geometry were caused by different fibre orientation distributions. Synchrotron light micro‐tomography allowed for visualisation of local fibre orientation at notches and the obtained images of the internal structure of the samples were subsequently analyzed by a global morphological parameter, the Mean Intercept Length. Results were also discussed in light of the full displacement field measured by Digital Image Correlation.
Please cite this article as: Cosmi, F., Bernasconi, A., Sodini, N., Phase contrast micro-tomography and morphological analysis of a short carbon fibre reinforced polyamide, Composites Science and Technology (2010), doi: 10.1016/ j.compscitech.2010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
PHASE CONTRAST MICRO-TOMOGRAPHY AND MORPHOLOGICAL
ANALYSIS OF
ABSTRACTThe mechanical properties of components made of short fibre reinforced composites, generally obtained by injection moulding, are strongly linked to fibre orientation. Therefore, it is of great importance to be able to verify the results of manufacturing process simulations obtained by commercial software. From the experimental point of view, the definition of carbon short fibre structure within a polymeric matrix in a micro-tomography is a non-trivial task, as the X-rays absorption properties of the two phases are very similar. This paper presents how this problem was overcome by using phase contrast imaging techniques. High resolution fibre structure reconstructions could therefore be obtained. The reconstruction of a large sample volume by overlapping of successive tomographies was also discussed. Moreover, this work shows that the anisotropy identification techniques based on morphological parameters, previously introduced by some of the Authors for short glass fibre 2 reinforced polymers, can also be adopted for fibre arrangement identification in this type of materials.
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